The present invention relates to a thermal analyzer including a sample chamber and a detector chamber that houses a detector for detecting a physical change due to temperature of a sample stored in the sample chamber as a displacement.
In the thermal analyzer including the sample chamber and the detector chamber that houses the detector for detecting a physical change due to temperature of a sample stored in the sample chamber as a displacement, when a gas is fed, different kinds of gasses are used as an atmospheric gas in the sample chamber and am atmospheric gas in the detector chamber that is provided to be connected to the sample chamber via a tubular member. In particular, when an atmospheric gas around a sample contains water vapor, a purge gas for protecting this water moisture from condensing on the detector is introduced into the detector.
In such a case, in the conventional thermal analyzer, an exhaust port is provided in the middle between the sample chamber and the detector chamber such that the atmospheric gases and the purge gas join to be discharged out of the thermal analyzer (see, for example, Japanese Patent No. 3084472, FIG. 2 and JP-A-2002-148230, FIG. 1).
In the conventional thermal analyzer, although the two kinds of atmospheric gasses having passed the sample chamber and the detector chamber, respectively, join to be discharged, since the sample chamber and the detector chamber communicate with each other, there is a problem in that it is likely that a part of the gasses flow back to the sample chamber and the detector chamber to damage gas purge performance. As the atmospheric gas fed to the sample chamber, an inert gas or an atmospheric gas, which has interaction with a sample and affects a change in a physical amount of the sample, is often selected. A highly reactive gas or water vapor may be often contained in the atmospheric gas. In addition, a cracker gas generated from the sample may be contained in the atmospheric gas. Thus, in general, it is desirable that the thermal analyzer has a structure in which the atmospheric gas does not flow back to the detector chamber.
In the case in which the air having an adjusted water vapor pressure is fed into the sample chamber to measure a change in physical properties of the sample in an atmosphere subjected to humidity control, when the sample chamber comes into a high-temperature and high-humidity state with temperature of 80° C. and relative humidity of 60% to temperature of 90° C. and relative humidity of 90%, in the structure of the thermal analyzer for performing thermomechanical measurement (TMA) shown in FIG. 2 of Japanese Patent No. 3084472, water vapor of a high partial pressure flows to a position near an entrance on the detector side crossing the middle between sample chamber and the detector chamber. Consequently, it is likely that the water vapor is liquefied and water drops are generated on a wall surface in the middle or a surface of a sample tube or a bar probe that is closer to the detector chamber and has temperature close to a room temperature. There are problems in that, for example, a weight of the water drops adhering to the bar probe causes an error in measurement of a weight of the sample, a load applied to the sample changes to cause an error in measurement of a physical amount of the sample, and, since the thermal analyzer is constituted vertically in FIG. 2 of Japanese Patent No. 3084472, the water drops drop to a sample part below the thermal analyzer to make the relative humidity unstable.
It is an object of the invention to solve the problems and provide a thermal analyzer that prevents back-flow of atmospheric gases to a sample chamber or a detector chamber by clearly distinguishing a location where the atmospheric gasses are mixed in a process in which the atmospheric gasses join to be discharged, prevents generation of water drops by clarifying a mixing location such that a part of water vapor does not flow into the detector chamber side even in the case in which the inside of the sample chamber is subjected to humidity control to be brought into a high-temperature and high-humidity state, and makes it possible to also mix the water vapor and a dry gas on the detector chamber side to lower a concentration of a highly reactive gas or lower a partial pressure of the water vapor to make it less likely that water drops are generated.